Under the Clean Air Act, EPA is required to carry out a periodic review and revision, as appropriate, of the air quality criteria and the primary and secondary standards for six criteria air pollutants, which include oxides of nitrogen. EPA is currently reviewing the primary (health-based) standard for the Nitrogen Dioxide National Ambient Air Quality Standards (NAAQS).

EPA’s Office of Research and Development has requested a peer review of the Second External Review Draft of its Integrated Science Assessment for Oxides of Nitrogen – Health Criteria. The CASAC previously reviewed the first external review draft of the Agency's Integrated Science Assessment .The final Integrated Science Assessment is intended to provide a synthesis and evaluation of science relevent for reviewing and revising the primary (health-based) standard for the Nitrogen Dioxide NAAQS.